Not surprising that different national authorities might find different ways to accomplish the same result. Could be local differences, or trade groups applying pressure (i.e. a flex hose maker who made big contributions to an MP who married his sister) or just a different local tally of accidents.
Propane sniffers are a wonderful thing, but sometimes they go bad and THAT can drive you nuts. One more thing to buy, wire, and wait for it to go wrong. Easier and prettier to keep a couple of canaries in the bilge.
When the music stops--get off the boat. Quickly, and without making any sparks. :-)